Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

802
FXUS63 KLOT 081102
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
602 AM CDT Fri May 8 2026

.KEY MESSAGES...

- Occasional chances for scattered rain showers will continue
  into next week.

- Temperatures will gradually warm through Saturday before
  trending cooler Sunday into early next week.

&&

.DISCUSSION...
Issued at 229 AM CDT Fri May 8 2026

A broad longwave trough centered near James Bay will remain the
prominent feature across the Great Lakes region into early next
week, resulting in several additional periods of isolated to
scattered showers.

A WNW to ESE oriented mid-level front roughly around 600 hPa is
interacting with an area of moisture marginally sufficient to
generate an axis of showers across the southern CWA early this
morning. Though lapse rates above this layer are under 6C/KM and
IR cloud tops have remained mostly warmer than -20C, there have
been sporadic GLM flashes and a few IC/CG lightning strikes
over the past few hours. The axis of showers and perhaps a few
more instances of lightning will drift eastward, remaining
around or south of the Kankakee River, through daybreak.

A 700 hPa wave currently evident over the Nebraska panhandle
early this morning will quickly track eastward today. Though
surface-based moisture will be rather limited, deep mixing this
afternoon will likely tap into a more robust area of low/mid-
level moisture to the west to produce a growing area of high-
based showers with a few embedded lightning strikes around/east
of I-55 and south the Kankakee River Valley mid to late
afternoon. Deep inverted-V profiles also suggest that some of
the initial showers could be gusty before coverage increases
late in the afternoon. Also cannot rule out some sprinkles along
a slow-moving or stalled lake breeze boundary across northeast
Illinois mid-afternoon, but better mid-level moisture and
support will likely remain well south of this area.

Another (stronger) mid-level wave and cold front will cross the
area through the day Saturday. Depending on the exact timing of
the frontal passage, another period of isolated to widely
scatted high- based showers are possible across primarily
northeast Illinois and northwest Indiana mid to late afternoon.
Yet another wave approaching from the west Saturday night could
yield an axis of rain over the southern half of the CWA. Cooler
and drier conditions are expected Sunday and Monday. With high
pressure nearing from the northwest and dry conditions noted by
PWATs under 0.3 inches, another unseasonably chilly night with
some patchy/areas of frost for outlying area is in store Sunday
night.

There are some hints in the extended guidance that broad
ridging over the western CONUS will begin to edge eastward next
week. However, decent agreement with a stronger trough (and rain
chances) digging southeastward across the Great Lakes Tuesday
into early Wednesday will likely re-inforce, or at least slow
the departure of, the long-standing trough over eastern Canada.

Kluber

&&

.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 602 AM CDT Fri May 8 2026

There are no significant aviation weather concerns anticipated
through the period.

VFR conditions are expected through the period as the focus for
showers today largely remains south of the terminals. Winds
will be light (5 kt or less) and somewhat variable this morning,
but directions will gradually focus into a south-southwesterly
direction at 7 to 10 kt for the afternoon and evening hours.
While we will have to keep an eye on the evolution of the lake
breeze boundary this afternoon, all indications at this time
continue to point at it remaining east of the main Chicago
terminals.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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